resample.c

MIDI解码程序(用VC编写)

	    newt_coeffs[i][0] = newt_coeffs[i-1][0] / i;
	    newt_coeffs[i][i] = newt_coeffs[i-1][0] / i;
	}

    	for (j = 1; j < i; j++)
    	{
    	    newt_coeffs[i][j] = newt_coeffs[i-1][j-1] + newt_coeffs[i-1][j];

	    if (i > 1)
	    	newt_coeffs[i][j] /= i;
	}
    }
    for (i = 0; i <= n; i++)
    	for (j = 0, sign = pow(-1, i); j <= i; j++, sign *= -1)
    	    newt_coeffs[i][j] *= sign;
}
#endif /* NOT USED */

/* initialize the coefficients of the current resampling algorithm */
void initialize_resampler_coeffs(void)
{
    /* initialize_newton_coeffs(); */
    initialize_gauss_table(gauss_n);
    /* we don't have to initialize newton table any more */

    /* bounds checking values for the appropriate sample types */
    /* this is as good a place as any to initialize them */
    if (play_mode->encoding & PE_24BIT)
    {
    	sample_bounds_min = -8388608;
    	sample_bounds_max = 8388607;
    }
    else /* 16-bit */
    {
    	sample_bounds_min = -32768;
    	sample_bounds_max = 32767;
    }
}

/* change the parameter for the current resampling algorithm */
int set_resampler_parm(int val)
{
    if (cur_resample == resample_gauss) {
	if (val < 1 || val > 34)
	    return -1;
	else
	    gauss_n = val;
    } else if (cur_resample == resample_newton) {
	if (val < 1 || val > 57)
	    return -1;
	else if (val % 2 == 0)
	    return -1;
	else {
	    newt_n = val;
	    /* set optimal value for newt_max */
	    newt_max = newt_n * 1.57730263158 - 1.875328947;
	    if (newt_max < newt_n)
		    newt_max = newt_n;
	    if (newt_max > 57)
		    newt_max = 57;
	}
    }
    return 0;
}

/*************** resampling with fixed increment *****************/

static resample_t *rs_plain_c(int v, int32 *countptr)
{
    Voice *vp = &voice[v];
    resample_t *dest = resample_buffer + resample_buffer_offset;
	sample_t *src = vp->sample->data;
    int32 ofs, count = *countptr, i, le;

    le = (int32)(vp->sample->loop_end >> FRACTION_BITS);
    ofs = (int32)(vp->sample_offset >> FRACTION_BITS);

    i = ofs + count;
    if(i > le)
	i = le;
    count = i - ofs;

	for (i = 0; i < count; i++) {
		dest[i] = src[i + ofs];
	}

    ofs += count;
    if(ofs == le)
    {
	vp->timeout = 1;
	*countptr = count;
    }
    vp->sample_offset = ((splen_t)ofs << FRACTION_BITS);
    return resample_buffer + resample_buffer_offset;
}

static resample_t *rs_plain(int v, int32 *countptr)
{
  /* Play sample until end, then free the voice. */
  Voice *vp = &voice[v];
  resample_t *dest = resample_buffer + resample_buffer_offset;
  sample_t *src = vp->sample->data;
  splen_t
    ofs = vp->sample_offset,
    ls = 0,
    le = vp->sample->data_length;
  resample_rec_t resrc;
  int32 count = *countptr, incr = vp->sample_increment;
#ifdef PRECALC_LOOPS
  int32 i, j;
#endif

  if(vp->cache && incr == (1 << FRACTION_BITS))
      return rs_plain_c(v, countptr);

  resrc.loop_start = ls;
  resrc.loop_end = le;
  resrc.data_length = vp->sample->data_length;
#ifdef PRECALC_LOOPS
  if (incr < 0) incr = -incr; /* In case we're coming out of a bidir loop */

  /* Precalc how many times we should go through the loop.
     NOTE: Assumes that incr > 0 and that ofs <= le */
  i = PRECALC_LOOP_COUNT(ofs, le, incr);

  if (i > count)
    {
      i = count;
      count = 0;
    }
  else count -= i;

  for(j = 0; j < i; j++)
    {
      RESAMPLATION;
      ofs += incr;
    }

  if (ofs >= le)
    {
      FINALINTERP;
      vp->timeout = 1;
      *countptr -= count;
    }
#else /* PRECALC_LOOPS */
    while (count--)
    {
      RESAMPLATION;
      ofs += incr;
      if (ofs >= le)
	{
	  FINALINTERP;
	  vp->timeout = 1;
	  *countptr -= count;
	  break;
	}
    }
#endif /* PRECALC_LOOPS */

  vp->sample_offset = ofs; /* Update offset */
  return resample_buffer + resample_buffer_offset;
}

static resample_t *rs_loop_c(Voice *vp, int32 count)
{
  int32
    ofs = (int32)(vp->sample_offset >> FRACTION_BITS),
    le = (int32)(vp->sample->loop_end >> FRACTION_BITS),
    ll = le - (int32)(vp->sample->loop_start >> FRACTION_BITS);
  resample_t *dest = resample_buffer + resample_buffer_offset;
  sample_t *src = vp->sample->data;
  int32 i, j;

  while(count)
  {
      while(ofs >= le)
	  ofs -= ll;
      /* Precalc how many times we should go through the loop */
      i = le - ofs;
      if(i > count)
	  i = count;
      count -= i;
	  for (j = 0; j < i; j++) {
		  dest[j] = src[j + ofs];
	  }
      dest += i;
      ofs += i;
  }
  vp->sample_offset = ((splen_t)ofs << FRACTION_BITS);
  return resample_buffer + resample_buffer_offset;
}

static resample_t *rs_loop(Voice *vp, int32 count)
{
  /* Play sample until end-of-loop, skip back and continue. */
  splen_t
    ofs = vp->sample_offset,
    ls, le, ll;
  resample_rec_t resrc;
  resample_t *dest = resample_buffer + resample_buffer_offset;
  sample_t *src = vp->sample->data;
#ifdef PRECALC_LOOPS
  int32 i, j;
#endif
  int32 incr = vp->sample_increment;

  if(vp->cache && incr == (1 << FRACTION_BITS))
      return rs_loop_c(vp, count);

  resrc.loop_start = ls = vp->sample->loop_start;
  resrc.loop_end = le = vp->sample->loop_end;
  ll = le - ls;
  resrc.data_length = vp->sample->data_length;

#ifdef PRECALC_LOOPS
  while (count)
    {
      while (ofs >= le)	{ofs -= ll;}
      /* Precalc how many times we should go through the loop */
      i = PRECALC_LOOP_COUNT(ofs, le, incr);
      if (i > count) {
		  i = count;
		  count = 0;
	  } else {count -= i;}
      for(j = 0; j < i; j++) {
		  RESAMPLATION;
		  ofs += incr;
	  }
    }
#else
  while (count--)
    {
      RESAMPLATION;
      ofs += incr;
      if (ofs >= le)
	ofs -= ll; /* Hopefully the loop is longer than an increment. */
    }
#endif

  vp->sample_offset = ofs; /* Update offset */
  return resample_buffer + resample_buffer_offset;
}

static resample_t *rs_bidir(Voice *vp, int32 count)
{
#if SAMPLE_LENGTH_BITS == 32
  int32
#else
  splen_t
#endif
    ofs = vp->sample_offset,
    le = vp->sample->loop_end,
    ls = vp->sample->loop_start;
  resample_t *dest = resample_buffer + resample_buffer_offset;
  sample_t *src = vp->sample->data;
  int32 incr = vp->sample_increment;
  resample_rec_t resrc;

#ifdef PRECALC_LOOPS
#if SAMPLE_LENGTH_BITS == 32
  int32
#else
  splen_t
#endif
    le2 = le << 1,
    ls2 = ls << 1;
  int32 i, j;
  /* Play normally until inside the loop region */

  resrc.loop_start = ls;
  resrc.loop_end = le;
  resrc.data_length = vp->sample->data_length;

  if (incr > 0 && ofs < ls)
    {
      /* NOTE: Assumes that incr > 0, which is NOT always the case
	 when doing bidirectional looping.  I have yet to see a case
	 where both ofs <= ls AND incr < 0, however. */
      i = PRECALC_LOOP_COUNT(ofs, ls, incr);
      if (i > count)
	{
	  i = count;
	  count = 0;
	}
      else count -= i;
      for(j = 0; j < i; j++)
	{
	  RESAMPLATION;
	  ofs += incr;
	}
    }

  /* Then do the bidirectional looping */

  while(count)
    {
      /* Precalc how many times we should go through the loop */
      i = PRECALC_LOOP_COUNT(ofs, incr > 0 ? le : ls, incr);
      if (i > count)
	{
	  i = count;
	  count = 0;
	}
      else count -= i;
      for(j = 0; j < i; j++)
	{
	  RESAMPLATION;
	  ofs += incr;
	}
      if(ofs >= 0 && ofs >= le)
	{
	  /* fold the overshoot back in */
	  ofs = le2 - ofs;
	  incr *= -1;
	}
      else if (ofs <= 0 || ofs <= ls)
	{
	  ofs = ls2 - ofs;
	  incr *= -1;
	}
    }

#else /* PRECALC_LOOPS */
  /* Play normally until inside the loop region */

  if (ofs < ls)
    {
      while (count--)
	{
	  RESAMPLATION;
	  ofs += incr;
	  if (ofs >= ls)
	    break;
	}
    }

  /* Then do the bidirectional looping */

  if (count > 0)
    while (count--)
      {
	RESAMPLATION;
	ofs += incr;
	if (ofs >= le)
	  {
	    /* fold the overshoot back in */
	    ofs = le - (ofs - le);
	    incr = -incr;
	  }
	else if (ofs <= ls)
	  {
	    ofs = ls + (ls - ofs);
	    incr = -incr;
	  }
      }
#endif /* PRECALC_LOOPS */
  vp->sample_increment = incr;
  vp->sample_offset = ofs; /* Update offset */
  return resample_buffer + resample_buffer_offset;
}

/*********************** vibrato versions ***************************/

/* We only need to compute one half of the vibrato sine cycle */
static int vib_phase_to_inc_ptr(int phase)
{
  if (phase < VIBRATO_SAMPLE_INCREMENTS / 2)
    return VIBRATO_SAMPLE_INCREMENTS / 2 - 1 - phase;
  else if (phase >= 3 * VIBRATO_SAMPLE_INCREMENTS / 2)
    return 5 * VIBRATO_SAMPLE_INCREMENTS / 2 - 1 - phase;
  else
    return phase - VIBRATO_SAMPLE_INCREMENTS / 2;
}

static int32 update_vibrato(Voice *vp, int sign)
{
  int32 depth;
  int phase, pb;
  double a;
  int ch = vp->channel;

  if(vp->vibrato_delay > 0)
  {
      vp->vibrato_delay -= vp->vibrato_control_ratio;
      if(vp->vibrato_delay > 0)
	  return vp->sample_increment;
  }

  if (vp->vibrato_phase++ >= 2 * VIBRATO_SAMPLE_INCREMENTS - 1)
    vp->vibrato_phase = 0;
  phase = vib_phase_to_inc_ptr(vp->vibrato_phase);

  if (vp->vibrato_sample_increment[phase])
    {
      if (sign)
	return -vp->vibrato_sample_increment[phase];
      else
	return vp->vibrato_sample_increment[phase];
    }

  /* Need to compute this sample increment. */

  depth = vp->vibrato_depth;
  depth <<= 7;

  if (vp->vibrato_sweep && !channel[ch].mod.val)
    {
      /* Need to update sweep */
      vp->vibrato_sweep_position += vp->vibrato_sweep;
      if (vp->vibrato_sweep_position >= (1 << SWEEP_SHIFT))
	vp->vibrato_sweep=0;
      else
	{
	  /* Adjust depth */
	  depth *= vp->vibrato_sweep_position;
	  depth >>= SWEEP_SHIFT;
	}
    }

  if(vp->sample->inst_type == INST_SF2) {
  pb = (int)((lookup_triangular(vp->vibrato_phase *
			(SINE_CYCLE_LENGTH / (2 * VIBRATO_SAMPLE_INCREMENTS)))
	    * (double)(depth) * VIBRATO_AMPLITUDE_TUNING));
  } else {
  pb = (int)((lookup_sine(vp->vibrato_phase *
			(SINE_CYCLE_LENGTH / (2 * VIBRATO_SAMPLE_INCREMENTS)))
	    * (double)(depth) * VIBRATO_AMPLITUDE_TUNING));
  }

  a = TIM_FSCALE(((double)(vp->sample->sample_rate) *
		  (double)(vp->frequency)) /
		 ((double)(vp->sample->root_freq) *
		  (double)(play_mode->rate)),
		 FRACTION_BITS);

  if(pb < 0) {
      pb = -pb;
      a /= bend_fine[(pb >> 5) & 0xFF] * bend_coarse[pb >> 13];
	  pb = -pb;
  } else {
      a *= bend_fine[(pb >> 5) & 0xFF] * bend_coarse[pb >> 13];
  }
  a += 0.5;

  /* If the sweep's over, we can store the newly computed sample_increment */
  if (!vp->vibrato_sweep || channel[ch].mod.val)
    vp->vibrato_sample_increment[phase] = (int32) a;

  if (sign)
    a = -a; /* need to preserve the loop direction */

  return (int32) a;
}

static resample_t *rs_vib_plain(int v, int32 *countptr)
{
  /* Play sample until end, then free the voice. */
  Voice *vp = &voice[v];
  resample_t *dest = resample_buffer + resample_buffer_offset;
  sample_t *src = vp->sample->data;
  splen_t
    ls = 0,
    le = vp->sample->data_length,
    ofs = vp->sample_offset;
  resample_rec_t resrc;
    
  int32 count = *countptr, incr = vp->sample_increment;
  int cc = vp->vibrato_control_counter;

  resrc.loop_start = ls;
  resrc.loop_end = le;
  resrc.data_length = vp->sample->data_length;
  /* This has never been tested */

  if (incr < 0) incr = -incr; /* In case we're coming out of a bidir loop */

  while (count--)
    {